rs6000: Save the PIC reg when needed

The PIC reg (r30) needs to be saved whenever the prologue sets it up,
not just if it is used elsewhere in the function.  Without this patch
the prologue for such a function will modify r30 without saving it
first, leading to disaster back in its callers.  This happened in the
testsuite for -m32 libgfortran and libstdc++, bootstrapped with -mlra,
many hundred times.

2015-10-29  Segher Boessenkool  <segher@kernel.crashing.org>

	* config/rs6000/rs6000.c (rs6000_reg_live_or_pic_offset_p): Move this
	function earlier in the file.
	(first_reg_to_save): Use rs6000_reg_live_or_pic_offset_p instead of
	df_regs_ever_live_p.

From-SVN: r229552

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 75ba2e83d4494c8ddde29450cbd2537ba6ef6f63..50fc56f022d1da5edf3c52083cccde7e9f9ac276 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2015-10-29  Segher Boessenkool  <segher@kernel.crashing.org>
+
+       * config/rs6000/rs6000.c (rs6000_reg_live_or_pic_offset_p): Move this
+       function earlier in the file.
+       (first_reg_to_save): Use rs6000_reg_live_or_pic_offset_p instead of
+       df_regs_ever_live_p.
+
 2015-10-29  Segher Boessenkool  <segher@kernel.crashing.org>
 
        * lra-constraints.c (process_address_1): Handle (mem:BLK (scratch))

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 21b43476181ec11a3b1336584ed8876201363095..bbdd1425eebb6da6675a746618e1eefd26b77a2a 100644 (file)
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -22016,6 +22016,27 @@ save_reg_p (int r)
   return !call_used_regs[r] && df_regs_ever_live_p (r);
 }
 
+/* Determine whether the gp REG is really used.  */
+
+static bool
+rs6000_reg_live_or_pic_offset_p (int reg)
+{
+  /* If the function calls eh_return, claim used all the registers that would
+     be checked for liveness otherwise.  This is required for the PIC offset
+     register with -mminimal-toc on AIX, as it is advertised as "fixed" for
+     register allocation purposes in this case.  */
+
+  return (((crtl->calls_eh_return || df_regs_ever_live_p (reg))
+           && (!call_used_regs[reg]
+               || (reg == RS6000_PIC_OFFSET_TABLE_REGNUM
+                  && !TARGET_SINGLE_PIC_BASE
+                   && TARGET_TOC && TARGET_MINIMAL_TOC)))
+          || (reg == RS6000_PIC_OFFSET_TABLE_REGNUM
+             && !TARGET_SINGLE_PIC_BASE
+              && ((DEFAULT_ABI == ABI_V4 && flag_pic != 0)
+                  || (DEFAULT_ABI == ABI_DARWIN && flag_pic))));
+}
+
 /* Return the first fixed-point register that is required to be
    saved. 32 if none.  */
 
@@ -22033,7 +22054,7 @@ first_reg_to_save (void)
       && ((DEFAULT_ABI == ABI_V4 && flag_pic != 0)
          || (DEFAULT_ABI == ABI_DARWIN && flag_pic)
          || (TARGET_TOC && TARGET_MINIMAL_TOC))
-      && df_regs_ever_live_p (RS6000_PIC_OFFSET_TABLE_REGNUM))
+      && rs6000_reg_live_or_pic_offset_p (RS6000_PIC_OFFSET_TABLE_REGNUM))
     first_reg = RS6000_PIC_OFFSET_TABLE_REGNUM;
 
 #if TARGET_MACHO
@@ -24232,27 +24253,6 @@ rs6000_emit_move_from_cr (rtx reg)
   emit_insn (gen_movesi_from_cr (reg));
 }
 
-/* Determine whether the gp REG is really used.  */
-
-static bool
-rs6000_reg_live_or_pic_offset_p (int reg)
-{
-  /* If the function calls eh_return, claim used all the registers that would
-     be checked for liveness otherwise.  This is required for the PIC offset
-     register with -mminimal-toc on AIX, as it is advertised as "fixed" for
-     register allocation purposes in this case.  */
-
-  return (((crtl->calls_eh_return || df_regs_ever_live_p (reg))
-           && (!call_used_regs[reg]
-               || (reg == RS6000_PIC_OFFSET_TABLE_REGNUM
-                  && !TARGET_SINGLE_PIC_BASE
-                   && TARGET_TOC && TARGET_MINIMAL_TOC)))
-          || (reg == RS6000_PIC_OFFSET_TABLE_REGNUM
-             && !TARGET_SINGLE_PIC_BASE
-              && ((DEFAULT_ABI == ABI_V4 && flag_pic != 0)
-                  || (DEFAULT_ABI == ABI_DARWIN && flag_pic))));
-}
-
 /* Return whether the split-stack arg pointer (r12) is used.  */
 
 static bool